Some stickers are packed into exactly packets of 9.
If the stickers are repacked into packets of 10,
there are 7 less packets.
- How many packets are there?
- How many stickers are there?
|
Packets of 9 |
Packets of 10 |
Number |
1 u |
1 u - 7 |
Value |
9 |
10 |
Total value |
9 u |
10(1 u - 7) = 10 u - 70 |
(a)
Let the number of packets of 9 be 1 u.
Number of stickers in packets of 9
= 1 u x 9
= 9 u
Number of stickers in packets of 10
= 10 x (1 u - 7)
= 10 u - 70
9 u = 10 u - 70
10 u - 9 u = 70
1 u = 70
1 u = 70 ÷ 1 = 70
Number of packets of 9 = 70
(b)
Number of stickers
= 9 u
= 9 x 70
= 630
Answer(s): (a) 70; (b) 630